Steam Generator Comprising a Swirling Device

ABSTRACT

The invention relates to a steam generator ( 1 ) comprising an evaporation tank ( 2 ) which is provided with a base ( 21 ) and a water outlet ( 22 ). A heating device ( 3 ) is arranged in said evaporation tank ( 2 ) and an impeller ( 4 ) is arranged under said heating device ( 3 ), as a swirling device. The water outlet ( 22 ) is arranged in the base ( 21 ) of the evaporation tank ( 2 ) and the impeller ( 4 ) is arranged in the water outlet ( 22 ). Due to the inventive arrangement of the water outlet ( 22 ) and the impeller ( 4 ), which rotates in an essentially continuous manner when in operation, a whirl is produced in the water of the evaporation tank ( 2 ) and, in particular, in the water outlet ( 22 ). As a result, limescale which is present in the water, in particular, in the region of the water outlet ( 22 ) is continuously displaced and maintained in suspension in small particle sizes.

The present invention relates to a steam generator comprising a swirling device, as defined in the preamble of the independent patent claim 1.

Steam generators are used, for example, for air humidification and conventionally comprise an evaporation vessel which is partially filled with water. The water is heated by means of a heating device, such as, for example, electrodes or electrical resistors, and is evaporated, mineral salts being precipitated which are removed from time to time from the evaporation vessel by blow-down. For this purpose, the evaporation vessel has a water outflow which, for example, in a steam generator disclosed in U.S. Pat. No. 4,221,955, is arranged in a sidewall of the evaporation vessel.

A major problem arising, above all, when water with a very high lime content is used is furring and the rapid clogging of the usually relatively small water outflow port and also the sedimentation of lime on the bottom of the evaporation vessel, which often make complicated cleaning necessary even after a short time.

In the steam generator disclosed in U.S. Pat. No. 4,221,955, although an impeller arranged as a swirling device above the evaporation vessel bottom reduces the sedimentation of lime, this is nevertheless prevented just as little as the furring of the water outflow. To be precise, the impeller is not used for this purpose, but, instead, for increasing the steam power, without more water being added. This steam power increase is based on the fact that, during the rotation of the impeller, the water surface is deformed conically in the form of a vortex, thus increasing the electrode penetration depth and therefore the steam power. By the impeller being switched off, the water level is lowered again, with the result that the steam production is reduced or even interrupted completely. The sedimentation of lime then commences in full again. When the steam generator is in normal operation, the impeller is switched on and off frequently, and therefore lime sedimentation is reduced only temporarily. Moreover, the action of the impeller scarcely reaches as far as to the in an evaporation vessel sidewall arranged water outflow, so that the furring of the water outflow is not prevented.

In view of the problem of the rapid need, with some types of water, for a complicated cleaning of the steam generator due to the furring of the water outflow and the sedimentation of lime in the steam generators known hitherto, the object on which the invention is based is to provide a steam generator of the type initially mentioned, in which a complicated delimiting, with associated steam generator standstill times, has to be carried out less often.

This object is achieved by means of the steam generator according to the invention, as defined in the independent patent claim 1. Preferred design variants may be gathered from the dependent patent claims.

The essence of the invention is as follows: a steam generator comprises an evaporation vessel which has a bottom and a water outflow. A heating device is arranged in the evaporation vessel and a swirling device is arranged beneath the heating device. According to the invention the water outflow is arranged in the bottom of the operation vessel and the swirling device is arranged in and/or vertically above the water outflow.

By virtue of the arrangement according to the invention of the water outflow and of the swirling device, which runs virtually continuously during operation, a vortex is generated in the water of the evaporation vessel and, in particular, in the water outflow during operation. Thus, the lime is moved continuously, particularly in the region of the water outflow, and is thereby held in suspension with a small particle size. At the same time, water also flows at a relatively high velocity around that part of the heating device which has penetrated into the water, thus likewise counteracting a deposition of lime.

By the lime being held in suspension, the growth of large lime crystals can be prevented, and there is less sedimentation of lime on the evaporation vessel bottom. A rapid furring of the water outflow and of the heating device is prevented. Moreover, the lime held in suspension can be blown down more simply, to which the vortex in the water outflow, which generates a suction effect, also contributes.

Preferably, in the steam generator according to the invention, the swirling device is arranged completely in the water outflow. This results in a suction effect which is optimal for blow-down, and, moreover, a furring of the water outflow can be virtually ruled out.

Advantageously, the water outflow is arranged centrically in the bottom of the evaporation vessel. This allows optimal blow-down and, together with a centric arrangement of the swirling device, results in an optimal formation of the water vortex which occurs during operation and which thus ideally covers the entire water present in the evaporation vessel.

Preferably, the bottom of the evaporation vessel is of funnel-shaped design. This, on the one hand, leads to a diversion of the vortex energy generated by the swirling device mainly in the direction of the heating device and thus ensures an intensive flow around the latter. On the other hand, the funnel shape additionally prevents calm zones with a tendency to lime deposits.

Preferably, the water outflow has arranged in it a funnel-shaped part, into which the swirling device projects from below. By means of such a funnel-shaped contour, the vortex energy generated by the swirling device can be conducted in an even more directed manner in the direction of the heating device.

Advantageously, the funnel-shaped part is of sieve-like design and subdivides the water outflow into an evaporation vessel-side part and a water outlet-side part. The sieve-like funnel-shaped part thus affords a protected zone for the water outlet-side part, in that it intercepts large lime fragments falling down and does not allow them to pass. Thus, for example, a water outlet port or water inflow port in the water outlet-side part can be safeguarded against being blocked by large lime fragments.

In a preferred design variant, the swirling device is an impeller. Such an impeller, while having a simple construction, generates an optimal vortex.

Advantageously, the impeller has blades which are located essentially within the funnel-shaped part, and also blades which are located essentially beneath the funnel-shaped part in the water outlet-side part of the water outflow. By means of such a two-tiered impeller, on the one hand a main vortex can be generated, which keeps the lime particles in the evaporation vessel small and in suspension and ensures a good flow around the heating device. On the other hand, at the same time, the water in the water outlet-side part of the water outflow, via which blow-down can take place or to which water can be supplied, can consequently be kept intensively in motion.

In an alternative advantageous design variant, the swirling device is a worm wheel, a swash plate or a swirler having a plurality of lamellae. An efficient vortex can also be generated by means of such simple swirling devices.

Advantageously, the drive of the swirling device takes place via a radially acting magnetic clutch. The swirling device can thus be driven by a motor arranged outside the evaporation vessel, without the vessel wall having to be penetrated by a mechanical part. Complicated seals can thereby be avoided. Moreover, the risk that at the same time a blocked swirling device, e.g. blocked by furring, blocks the motor, which could damage the latter, is avoided.

Preferably, the steam generator according to the invention has, for the outflow water flowing out from the water outflow, a separation device for the separation of water and lime. Consequently, the comparatively small lime particles can be intercepted before they pass into the blow-down piping leading further on, possibly sink down there and lead to blockages.

The heating device advantageously comprises two electrodes or at least one resistance heating element.

The steam generator according to the invention is described in more detail below by means of exemplary embodiments, with reference to the accompanying drawings in which:

FIG. 1—shows a first exemplary embodiment of a steam generator according to the invention in a partially sectional perspective view;

FIG. 2—shows a sectional view of a lower part of the steam generator of FIG. 1;

FIG. 3—shows an exploded view of the impeller, of the water outflow and of the drive of the steam generator of FIG. 1;

FIG. 4—shows the steam generator parts of FIG. 3 in assembled form in a partially sectional perspective view;

FIG. 5—shows a lower part of the steam generator of FIG. 1 with a separation device in the form of a settling tank in a partially sectional perspective view;

FIG. 6—shows a lower part of the steam generator of FIG. 1 with a separation device in the form of a filter device in a partially sectional perspective view;

FIG. 7—shows the lower part of the steam generator with a filter device of FIG. 6 in a sectional view;

FIG. 8—shows a sectional view of a lower part of a steam generator according to the invention in a second exemplary embodiment;

FIG. 9—shows the impeller of the steam generator of FIG. 8;

FIG. 10—shows a sectional view of a lower part of a steam generator according to the invention without a magnetic clutch, according to a third exemplary embodiment;

FIG. 11—shows schematically a lower part of a steam generator according to the invention in a fourth exemplary embodiment;

FIG. 12—shows a swirling device in the form of a worm wheel;

FIG. 13—shows a swirling device in the form of a swash plate; and

FIG. 14—shows a swirling device in the form of a swirler having a plurality of lamellae.

In the exemplary embodiment illustrated in FIG. 1 to 4, a steam generator 1 according to the invention comprises an evaporation vessel 2 with a funnel-shaped bottom 21, with an essentially cylindrical sidewall 23 and with a top 24. Within the evaporation vessel 2 is arranged a heating device 3 comprising a plurality of electrodes 31 which are fastened to the top 24 and have electrical supply terminals 311 which project outwards through the top 24.

A water outflow 22 is arranged centrically in the bottom 21 of the evaporation vessel 2. For this purpose, in the middle of the bottom 21, a port is formed, which is delimited laterally by annular bottom parts 221 and 222 projecting approximately vertically upward and downward. An outflow housing has an essentially cylindrical wall 223 which starts on the outside on the annular bottom part 222 and which extends downward from there. An O-ring seal 26 is held between the essentially cylindrical wall 223, the downwardly projecting annular bottom part 222 and a ring part 25. An outflow housing bottom 224 delimits downwardly the water outflow 22 which carries water during operation.

A funnel-shaped part 5, and, as a swirling device, an impeller 4 which projects from below into the funnel-shaped pipe 5 are arranged in the outflow housing. The funnel-shaped part 5 is of sieve-like design and subdivides the water outflow 22 into an evaporation vessel-side part and a water outlet-side part. It is carried by a supporting cylinder 51 which sits on the outflow housing bottom 224. The funnel-shaped part 5, on the one hand, allows the water to pass from above downward and from below upward and, on the other hand, ensures that lime fragments which are too large do not pass into the water outlet-side part. Moreover, the funnel shape conducts the water stream and the vortex energy in a directed manner in the direction of the heating device 3 during operation.

For topping up the evaporation vessel 2 with fresh water, a water inflow 6 passes through the cylindrical wall 223 of the outflow housing and the supporting cylinder 51 of the funnel-shaped part 5. Moreover, for blow-down these are provided with water outlet ports 71 and 72, to which a water outlet duct 7 is connected. The transition from the water outlet port 71 to the water outlet duct 7 can be closed by means of a magnet valve 73 having a valve housing 731 in which are arranged a fixed magnetic part 732 and a valve armature 733 adjustable with respect to the latter. The transition is opened for the blow-down of lime-containing water from the evaporation vessel 2, which transition otherwise normally remains closed.

The form of the impeller 4 can best be seen from FIGS. 2 and 3. It comprises a smaller hollow cylinder-like basic body 42 which is arranged on a larger hollow cylinder-like basic body 43. Four blades 41 which are located essentially within the funnel-shaped part 5 extend radially outward from the smaller hollow cylinder-like basic body 42 and, during operation, generate a main vortex which keeps the lime particles in the evaporation vessel 2 small and in suspension and ensures a good flow around the heating device 3. Four blades 45, which are located essentially beneath the funnel-shaped part 5 in the water outlet-side part of the water outflow 22 and which keep water in the water outlet-side part of the water outflow 22 in motion, extend radially outward from the larger hollow cylinder-like basic body 43.

The smaller hollow cylinder-like basic body 42 surrounds a fastening cylinder 225 which projects upward from the outflow housing bottom 224 and into which is screwed a screw 47 which assumes the rotary mounting of the impeller 4, that is to say prevents a removal of the impeller 4 from the outflow housing bottom 224, without essentially hindering a rotation of the impeller 4. Moreover, the impeller 4 normally lies on the outflow housing bottom 224 via four feet 48 formed beneath the blades 45 on the hollow cylinder-like basic body 43.

The larger hollow cylinder-like basic body 43 surrounds a hollow-cylindrical elevation in the middle of the outflow housing bottom 224. Moreover, it has a multiplicity of recesses 44, in each of which a permanent magnet 46 is arranged. This forms the impeller-side part of a radially acting magnetic clutch for transmitting the drive force from a drive 8 to the impeller 4. The drive 8 comprises a motor 81 with a drive shaft 82, to the upper end of which is fastened a magnetic drum 84 having recesses 85 in each of which a permanent magnet 83 is arranged. The magnetic drum 84 is located in the hollow-cylindrical elevation in the middle of the outflow housing bottom 224 and, during rotation, drives the impeller 4 via the permanent magnets 83 and 46. A ventilator wheel 86, which acts as a cooling blower and is fastened directly on the motor drive shaft 82, ensures the cooling of the motor 81.

FIG. 5 shows the lower part of the steam generator 1 with a separation device for separation of water and lime in the form of a settling tank 9. The settling tank 9 is essentially a water vessel with three vessel parts 93, 94 and 95 separated by two partitions 91 and 92 and with a water outlet port 96. The lime-containing water blown down from the evaporation vessel 2 passes via the water outlet duct 7 and a water outlet port 74 into the first vessel part 93 and fills the latter until the water flows over the partition 91 into the second vessel part 94. When the second vessel part 94 is full, the water flows over the partition 92 into the third vessel part 95 and fills the latter up to the water outlet port 96. Finally, the water passes from the water outlet port 96 into the line network. The lime particles can settle in the three vessel parts 93, 94 and 95 and are thus separated from the overflowing water. The settling tank 9 must either be cleaned or be replaced from time to time.

FIGS. 6 and 7 illustrate an alternative separation device for the separation of water and lime in the form of a filter device 109. The filter device 109 comprises essentially a water-permeable filter bag 191 which is fastened to a water supply disk 192. The water supply disk 192 lies removably on a shoulder 1931 of an otherwise essentially cylindrical container 193. Said water supply disk has an inflow port 1921 and a supply duct 1922, via which port and which duct lime-containing water is supplied to the filter bag 191 from the water outlet duct 7 and the water outlet port 74. The filter bag 191 allows the water to pass through and retains the lime. Therefore, it has to be replaced from time to time. A mesh disk 194 lying on an inner annular projection 1932 of the container 193 ensures that large fragments cannot pass into the container outlet 1933 in the event of an unintended release of the filter bag 191.

FIG. 8 shows a detail of a second exemplary embodiment of a steam generator 101 according to the invention. The only difference from the first exemplary embodiment is the impeller 104 which is also illustrated separately in FIG. 9. In contrast to the impeller 4, in the impeller 104, no blades extend outward from the larger hollow cylinder-like basic body 143. Moreover, feet are absent on the underside of the basic body 143. Finally, the permanent magnets are cast into the basic body 143. Otherwise, the impeller 104 corresponds to the impeller 4 of the first exemplary embodiment. In particular, four blades 141 extend radially outward from a smaller hollow cylinder-like basic body 142 and are located essentially within the funnel-shaped part 5.

FIG. 10 shows a detail of a steam generator 201 according to the invention according to a third exemplary embodiment. The difference from the first exemplary embodiment is that the impeller 204 is not driven via a magnetic clutch, but is directly connected mechanically to the drive shaft 282 of the motor 281. For this purpose, the drive shaft 282 is led through the outflow housing bottom 290, an annular shaft seal 291 ensuring sealing. Because of the mechanical connection of the drive shaft 282 and the impeller 204, there is no need for a magnetic drum and no need for the arrangement of permanent magnets in the impeller 204.

Instead, the impeller 204 comprises a cylindrical middle part 242 which extends from below upward and into which the drive shaft 282 is introduced. Four blades 241 extend radially outward from the upper half of the cylindrical middle part 242 and are located essentially within the funnel-shaped part 5. A further blade 245 in each case extends obliquely downward and outward from each of these four blades 241. These four blades 245 are located beneath the funnel-shaped part 5 in the water outlet-side part of the water outflow and keep the water there in motion.

The steam generator 201 otherwise corresponds to the steam generator 1 of the first exemplary embodiment.

In a steam generator 301 according to the invention in a fourth exemplary embodiment, part of which is illustrated diagrammatically in FIG. 11, the water outlet duct 307 is located directly beneath the impeller 304. In order to make such an arrangement possible, the magnetic drum 384 of the drive is arranged outside the water outflow 322 around said outflow and around the impeller 304 with the permanent magnets and with the blades 341. To close the water outflow 322, a magnet valve 373 is arranged in the latter.

FIG. 12 shows, as an alternative to an impeller, a swirling device in the form of a worm wheel 404, while FIG. 13 illustrates a swirling device in the form of a swash plate 504.

A further alternative swirling device in the form of a swirler 604 is shown in FIG. 14. The swirler 604 comprises a plurality of bent lamellae 641, the ends of which are screwed to a basic disk 642.

Further structural variations of the steam generators described above can be implemented within the scope of the patent claims. 

1. Steam generator with an evaporation vessel having a bottom and a water outflow, with a heating device arranged in the evaporation vessel, and with a swirling device arranged in the evaporation vessel beneath the heating device, characterized in that the water outflow is arranged in the bottom of the evaporation vessel, and the swirling device is arranged in and vertically above the water outflow or completely in the water outflow.
 2. Steam generator according to claim 1, characterized in that the swirling device is arranged completely in the water outflow.
 3. Steam generator according to claim 1, characterized in that the water outflow is arranged centrically in the bottom of the evaporation vessel.
 4. Steam generator according to claim 1, characterized in that the bottom of the evaporation vessel is of a funnel-shaped design.
 5. Steam generator according to claim 1, characterized in that the water outflow has arranged in it a funnel-shaped part, into which the swirling device projects from below.
 6. Steam generator according to claim 5, characterized in that the funnel-shaped part is of a sieve-like design and subdivides the water outflow into an evaporation vessel-side part and a water outlet-side part.
 7. Steam generator according to claim 1, characterized in that the drive of the swirling device takes place via a radially acting magnetic clutch.
 8. Steam generator according to claim 1, characterized in that the swirling device is an impeller.
 9. Steam generator according to claim 6, characterized in that the impeller has blades which are located essentially within the funnel-shaped part, and also blades which are located essentially beneath the funnel-shaped part in the water outlet-side part of the water outflow.
 10. Steam generator according to claim 1, characterized in that the swirling device is a worm wheel, a swash plate or a swirler having a plurality of lamellae.
 11. Steam generator according to claim 1, characterized in that, for the outflow water flowing out from the water outflow, it has a separation device for the separation of water and lime.
 12. Steam generator according to claim 1, characterized in that the heating device comprises at least two electrodes or at least one resistance heating element.
 13. Steam generator according to claim 8, characterized in that the impeller has blades which are located essentially within the funnel-shaped part, and also blades which are located essentially beneath the funnel-shaped part in the water outlet-side part of the water outflow. 